Drugs may be delivered to patients by a variety of methods including oral, intravenous, intramuscular, inhalation, topical, subcutaneous delivery or delivery directly or locally to the treatment site (e.g., intrathecally, intraspinally, intraarticularly, etc.). The method of delivery chosen depends, among other things, upon the condition being treated, desired therapeutic concentration of the drug to be achieved in the patient and the duration of drug concentration that must be maintained.
Recently, drug depots have been developed which allow a drug to be introduced or administered to sites beneath the skin of a patient so that the drug is slowly released over a long period of time. Such drug depots allow the drug to be released from the depot in a relatively uniform dose over weeks, months or even years. This method of administering drugs is becoming especially important for contraceptives and cancer drugs that are implanted subcutaneously.
Sometimes, after the drug depot is implanted at the treatment site, the drug depot may migrate from the implant site prior to surgical closure (e.g., floats off in blood or shifts as tissues are repositioned during surgical site closure) or as physiological conditions change (e.g., repair and regeneration of cells, tissue ingrowth, movement at implant site, etc.). At times, this may reduce efficacy of the drug as the drug depot migrates away from the implant site and lodges in a distant site. If this occurs, the drug depot will have to be removed from the distant site and have to be reinserted causing additional physical and psychological trauma to a patient. In some cases, if the drug depot migrates into a joint, the drug depot may inhibit movement. In more severe cases, if the drug depot migrates, it may restrict blood flow causing an ischemic event (e.g., embolism, necrosis, infarction, etc.), which could be detrimental to the patient.
Postoperative pain tends to be a difficult condition to treat and may be detrimental to the patient if not properly treated. The site of the surgery has a profound effect upon the degree of postoperative pain a patient may suffer. In general, operations on the thorax and upper abdomen are more painful than operations on the lower abdomen, which in turn are more painful than peripheral operations on the limbs. However, any operation involving a body cavity, large joint surfaces, the spine or deep tissues should be regarded as painful. In particular, operations on the thorax or upper abdomen may produce widespread changes in pulmonary function, an increase in abdominal muscle tone and an associated decrease in diaphragmatic function. The result will be an inability to cough and clear secretions, which may lead to lung collapse and pneumonia. Prolonged pain can reduce physical activity and lead to venous stasis and an increased risk of deep vein thrombosis and consequently pulmonary embolism. In addition, there can be widespread effects on gut and urinary tract motility, which may lead in turn to postoperative ileus, nausea, vomiting and urinary retention. These problems are unpleasant for the patient and may prolong hospital stay and are exacerbated if after implantation the drug depot migrates away from the implant site.
New drug depot compositions and methods are needed, which can easily allow accurate and precise placement of a drug depot. When implanting several drug depots at a time, drug depot compositions and methods are needed that accurately and precisely allow placement of the drug depot in a manner that optimizes location, accurate spacing, and drug distribution. New drug depot compositions and methods are also needed to effectively treat post-operative pain.